We finally know what Paul McCartney was singing about in Hard Day’s Night.

“I’m heavily into S&M,” the 76-year-old former Beatle quips.

Paul revisited his former school, the Liverpool Institute for Performing Arts, yesterday, where he reminisced – surprisingly fondly – about all the times he got the cane.

“This place is just full of so many memories,” he sighed to a live audience and Pulp frontman Jarvis Cocker.

“So many memories. Getting the cane for instance, which was a wonderful memory. I’m now heavily into S&M.”

McCartney joked that he enjoyed being caned (Image: Getty)

Paul teased, “I blame them – I grew to like it,” as he admitted he and late bandmate George Harrison would be sent to the head’s office for regular canings because they were “cheeky young Liverpool guys”.

“You would hold your hand out and he would give you what he called ‘six of the best’,” Paul remembered.

“He would just take this ruddy great rod and whack you – hence my love affair with S&M.”

Paul has just returned from a jaunt in Italy with his wife of seven years, Nancy Shevell, and is preparing to release “concept album” Egypt Station in September before heading off on tour.

Nancy’s favourite track on the record is a song he wrote about his guitar, which he’s called Confidante.

“It’s another of my perversions,” he added with a chuckle. “I write to guitars.”